Adds end-to-end tests for VrShell navigation transitions.

chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShell.java

Index: chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShell.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShell.java b/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShell.java
index 6184b5962df381651bbb9d717d6377d0f0254174..fa8104f227845cd933ac28af7cad23da666c9828 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShell.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShell.java
@@ -39,6 +39,11 @@ public interface VrShell {
     void setWebVrModeEnabled(boolean enabled);
 
     /**
+     * Returns true if we're presenting WebVR content.
+     */
+    boolean getWebVrModeEnabled();
+
+    /**
      * Returns the GVRLayout as a FrameLayout.
      */
     FrameLayout getContainer();